C/2017 T2 (PanSTARRS) is an Oort cloudcomet discovered on 2 October 2017[3] when it was 9.2 AU (1.38 billion km) from the Sun. The closest approach to Earth was on 28 December 2019 at a distance of 1.52 AU (227 million km). It came to perihelion (closest approach to the Sun) on 4 May 2020[2] when it was safe from disintegration at 1.6 AU from the Sun. (Mars is also roughly 1.6 AU from the Sun.)
Comet C/2017 T2 (PanSTARRS) brightened to apparent magnitude 8 and was visible with 50mm binoculars.[4][5] On 22-24 May 2020, the comet passed near the galaxy pair of Messier 81 and Messier 82, passing less than one degree from the latter.[6] In early June 2020 the comet was near the magnitude 1.8 star Dubhe in Ursa Major.[7]
Based on the light curve of the comet nucleus, it has been estimated that the nucleus has a rotational period of 5.6759 ± 0.0046 h.[8] The comet at perihelion had a water production of 6×1028 molecules/s. Also when observed in CN featured two side jets in June 2020, but they weren't observed one month later.[9] Concentric structures were observed in the inner coma in May 2020, probably created by a jet with rotation axis towards the Earth.[10]
JPL Horizons using an epoch 1950 orbit solution models that C/2017 T2 took millions of years to come from the Oort cloud at a distance of roughly 74,000 AU (1.2 ly).[1]